Search

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In power systems with a high proportion of renewable energy, to achieve coordinated optimal scheduling of source and load considering multiple uncertainties is an important issue in power system operation. Therefore, a probabilistic spinning reserve optimization model based on multiple scenarios is constructed. Multiple uncertain factors are considered in the model, such as wind power and solar power forecast errors, load forecast error and unscheduled generator outage. Renewable energy curtailment and load shedding are used as special reserve resources in the day-ahead security-constrained unit commitment (SCUC) to improve the economic operation efficiency. The calculations of reliability indexes, expected energy not served and expected energy curtailment, are simplified, and the inequality constraints related to these two indexes are reduced, which improves the computational performance of the model. The model optimizes the total expected cost considering multiple uncertainties. Case studies based on the IEEE-RTS demonstrate the effectiveness of the proposed model. The numerical results show that the improved calculation method of reliability indexes can effectively reduce the solution time of the SCUC model. The reserve optimization model can realize the dynamic allocation of the spinning reserve capacity of the system and improve economic operation of the system.

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the issue of spatial variability of soil mechanical parameters in slope stability analysis, this paper proposed a stochastic finite element method for calculating the distribution of FS（factor of safety） of embankment slopes, and Monte Carlo（MC） strength reduction combined method and MC direct method were proposed to calculate the reliability of slope. Taking isotropic two-dimensional slope as an example, firstly, sampling to get the corresponding random field of material properties, and then the slope displacement, stress and plasticity zone results were calculated; then on the basis of NMC times sampling of random field, the failure probability of the slope was obtained and the reliability index was solved and analyzed by the following methods of a) combined method（M1）: the strength reduction method was used to get the reduction coefficient of each sample and its distribution; b) MC direct method（M2）: using viscoplastic method to solve directly to judge the instability of slopes, and the instability cases under all sample conditions were counted. The results show that the slope stability analysis considering the material properties random field, the mean, variance, distribution of FS and reliability indexes are integrated to evaluate the slope safety, which can get the real and reliable slope stability analysis results. [ABSTRACT FROM AUTHOR]

Failure rate, average failure rate and average residual life determine the life distribution and reliability of structures, which play a very important role in the reliability research of mechanical products. Based on the basic in-dex of reliability measurement, the relationship between fatigue reliability coefficient and reliability is deduced when the life distribution is two parameter Weibull distribution. A method for calculating the structural failure rate and av-erage failure rate is proposed based on fatigue reliability coefficient, and the corresponding calculation process is de-rived. Based on the existing fatigue life test data of integral lap panel structure, the proposed method and the tradi-tional integral method are used to calculate the average failure rate and error analysis of integral lap panel structure.The results show that the derived calculation formula has a simple form, is easy to calculate, and has high accuracy.It is of great significance for FMECA (failure mode effects and criticality analysis) and maintenance decision-mak-ing of mechanical structure.

As a real time control system to ensure train traffic safety, rail transit signal products must have high reliability and high safety. In order to find out the weak links in the design of rail transit signal products in advance and provide data support for the selection and optimization of product design schemes, this paper takes the switch unit of system security computer platform in railway signaling products as an example to propose a reliability prevention method. At first, reliability block diagram and model are established. Then, the component stress method is used to predict its reliability. At last,according to the comparison between the reliability prediction results and the required reliability indexes, it evaluates whether the design method meets the requirements. The characteristic of this reliability prediction method is that it can make an objective comprehensive evaluation on the reliability level of products under the condition of comprehensively considering various reliability influencing factors. Application results show that the MTBF of the switch unit is 1 005 015 h, and its availability is 99.999 9%.The reliability index meets the specified requirements.

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Firstly,the concept of random events was introduced into the communication process,and the serial and parallel reliability algorithms were introduced.Secondly,the reliability design of virtual hosts,clusters and spine-leaf switching networks and their calculation methods were analyzed.Finally,the connection based on each component unit was analyzed.Based on the connection relationships among the components,the reliability design scheme of virtual nodes and its reliability algorithm was proposed.

The fault tree analysis is an effective method for reliability evaluation of the system. However, there are problems in the reliability calculation of independent power systems, such as the reliability parameters have large amount of calculation and are difficult to be solved. Thus, the fault tree minimum cut sequence set method is used to solve the reliability index of the independent power system. For the combinatorial explosion problem in the calculation of the reliability index of the system, a time-based operator is proposed to solve the minimum cut sequence set. In this way, the hierarchical module is used to simplify the dynamic fault tree model, and the minimum cut sequence set is obtained according to the logical operation rules of the minimum cut sequence set. Finally, the failure probability formula is used to solve and obtain the reliability index of the independent power system. Taking the reliability analysis of a conventional independent power system and B787 flight power system as an example, the feasibility and correctness of the proposed algorithm are verified, which provides a new idea for solving the reliability index of the independent power system. [ABSTRACT FROM AUTHOR]

There are a lot of reservoirs in China and the number of dangerous reservoirs is large. The dam break and non-dam break risk analysis and disposal of dangerous dams during the operation period is the key technology of reservoir operation management. According to the aging characteristics of dam materials and based on stochastic finite element method, the method to calculate and analyze the reliability of gravity dam was proposed. Taking HYT Hydropower Station as an example, the reliability indexes of anti-slide stability and strength of the non-overflow section on the left bank were calculated and analyzed. Meanwhile, how material parameter change with operation time was considered and then the time-history variation rule of reliability in operation period was analyzed. The results show that under the check flood level condition, the strength reliability index corresponding to uniaxial tension criterion of the masonry part of dam crest and the anti-slide stability reliability index are lower than the target reliability index 3.7, which need special attention. And with the increase of operation time, the reliability indexes of anti-slide stability and strength are decreased. This method has high calculation efficiency, many actual influence factors can be considered, and the results are in accordance with the actual law, which is reasonable and effective in analyzing the reliability of gravity dam. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Jilin University (Science Edition) / Jilin Daxue Xuebao (Lixue Ban) is the property of Zhongguo Xue shu qi Kan (Guang Pan Ban) Dian zi Za zhi She and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At present, the diversion tunnel is often used in the early stage of hydropower station construction, but the problem of water inrush often occurs in the process of excavation, so the determination and evaluation of the probability of water inrush has become the primary problem solved by geologists in recent years. For diversion tunnel water gushing limit characteristics, with the theory of reliability, determine its reliability limit state equation, and based on field test and probability statistics method, the equation of rock permeability coefficient K, diversion tunnel length L, the phreatic surface to the diversion tunnel bottom head height H, drain the water depth h, diversion tunnel radius R basic variables such as average, variation coefficient and the changing rule of the reliability index were studied. Diversion tunnel water gushing reliability index calculation model was established and at the same time it analyzed the reliability sensitivity of the basic variables. It obtains through the analysis that the reliability index of water inrush is the highest sensitivity to the permeability coefficient K of diversion tunnel rock mass, then is the phreatic surface to the aquifer water head height of the base plate, diversion tunnel length and radius of influence and the sensitivity to the drainage ditch water depth is the minimum. [ABSTRACT FROM AUTHOR]

Through the analysis of solar radiation, sunshine duration, ambient temperature, cloud cover and other environmental factors, the operation state transition of photovoltaic(PV) array in sunshine duration is obtained. According to the obtained annual cloud cover data, the probability statistics are carried out to obtain the probability distributions of different levels of cloud cover. Then the solar radiation is calculated when cloud cover is greater than zero by using the formula. The fault types of PV module can be divided into two categories: one is fault of PV module caused by manufacturing process, the other is fault of PV module caused by environmental factors. The output power of PV array is clustered to classify reliability states. The state transition probability matrix of PV array is obtained through model simulation. The validity of the reliability model for PV array is verified by an example. [ABSTRACT FROM AUTHOR]

Studies on failures of castellated beams have identified instability as a critical one. After reviewing the existing investigations, the buckling modes of castellated beams could be summarized into three categories ： lateraltorsional buckling, web post buckling and distortional buckling. Based on the studies on the stability of castellated beams published in recent 30 years, the main factors that influence the stability of castellated beams were investigated. The probability distribution and sensitivity of the influencing factors of simply supported castellated beams subjected to pure bending were obtained by using the Monte Carlo method. Furthermore, part of the representative test results were compared with the European code EN 1993-1-1 predictions. Based on the partial safety factor for resistance in Chinese specification GB 50068--2001 ' Unified standard for reliability design of building structures ' ， a calculation of reliability index of castellated beams experiencing lateral-torsional buckling under various loading conditions was conducted, which formed basis on the development of domestic specification on castellated beams. Finally, this paper summarized the shortcomings of the current research on the stability of castellated beams，and further research direction was pointed out. [ABSTRACT FROM AUTHOR]

After large-scale electric vehicle is connected to the distribution network，the load of the distribution network will increase，and then the power quality of the distribution network will be affected． Therefore，a reliability analysis method of power grid based on component failure rate change is proposed in combination with the actual change of component failure rate． According to various factors related to charging power demand，the charging power of the electric vehicle is modeled，and the load variation of the original distribution network caused by the access of electric vehicle to the distribution network in different scales is simulated． Considering the change of component failure rate，the Weibull distribution is used to model the bathtub curve of component failure rate． The reliability of power grid is evaluated by Monte Carlo method． In reliability analysis，the real-time failure rate of components is taken as the criterion． Taking the IEEE － RBTS Bus2 distribution system as an example，the reliability indexes of each load point change with time are analyzed and calculated，and the relationship between the reliability indexes and the time of the system under different scale electric vehicles connected to the distribution network is studied． The reliability index calculated by this method is closer to reality． [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper introduced testing method of mean time between failures, did site test of mean time between failures in four coal mines to the same coal mine monitoring system, and got mean time between failures of main equipments of the monitoring system. It concluded: the values of mean time between failures of intrinsic safety power, gas sensor, CO sensor and wind speed sensor are relatively small, and these equipments should be the focus of future design and improvement; the monitoring system can achieve the index suggested in AQ 6201—2006 that mean time between failures should be not less than 800 hours; statistical results show that line fault of underground coal mine occurs frequently.

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The definition of fatigue failure limit state for steel structures was given. The statistical parameters of both fatigue strength and fatigue load effect were analyzed on the basis of both literature investigation and site tests for fatigue load effect of steel crane girders. First-order second-moment method was used to calculate the fatigue reliability index. The values of partial factors for fatigue reliability design were investigated. It is concluded that fatigue strength standard deviations for twelve kinds of structural details (including influence of stress ratio) in steel crane girders are in the range of 0.025 1 to 0.0792, and the standard deviation of equivalent stress range is 0.0148 when its probability distribution follows lognormal distribution. The following design values are suggested： 2.9 for the fatigue reliability index, 1.0 for the partial factor of fatigue strength and 1.14 for the partial factor of fatigue load effect, respectively. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem of lack of indexes for the power secondary system reliability analysis in the smart substation, new indexes and index calculation method for the power secondary system reliability analysis were studied, and the common features of the power seconda­ry system in the smart substation were summarized according to the IEC61850 standard, and the steady unavailability of function(Us) , loss of function probability(LOFP) and expected functions not working(EFNW) were put forward as the reliability indexes, and a reliability sim­ulation algorithm was designed based on non-sequential monte carlo using matlab language. Finally, the reliability of the power secondary system in a T1-1 smart substation was evaluated by the built algorithm using the proposed reliability indexes, three cases which considering different structures and redundancy networks were practiced. The results indicate that the new indexes can reflect the function reliability and the system reliability of the power secondary system with good sensitivity and applicability, has an important guiding significance for reliability analysis of the power secondary system in the smart substation. [ABSTRACT FROM AUTHOR]

Based on the force transfer path analysis, the composite shear wall plays a very important role in terms of sustaining and transferring horizontal and vertical loads. From component to system, a relatively comprehensive review of the studies at home and abroad on the seismic performances of wall studs, fasteners and the composite shear wall is presented. A statistical analysis was implemented mainly based on the data of typical shear resistance experimental results at home and abroad of cold-formed thin-walled steel composite shear walls, indicating how the sheathing boards, fasteners, steel frame, aspect ratio, opening size and loading regime make influence on the shear performance of shear walls. Some experimental results were compared with the design guidance values of Chinese code finding that the design guidance values after linear interpolation make a conservative prediction of shear resistance with large spacing fasteners. The calculation of reliability index was made with the partial safety factor for resistance given in Chinese code, showing that the design guidance values of Chinese code can't satisfy the objective reliability index 3.2. The recalculated reliability index with partial safety factor for resistance adjusted according to a reference's recommendation are in good agreement with objective reliability index and there will be a lot of work remaining to do for a more appropriate value of partial safety factor for resistance. Some suggestions on the seismic performance research field of this kind of structures system are proposed. [ABSTRACT FROM AUTHOR]

In this paper, a k-out-of-n:G repairable system with a repair facility and one repairman who takes multiple vacations is studied. By using the Markov analysis method, we obtain the recursive expressions for the stationary state probabilities of our repairable system. Furthermore, some important performance characteristics such as the steady-state availability of the system, mean time to the first failure, failure frequency of the system, the probability for the repairman being busy, the steady-state unavailability of the repair facility, the expected number of failed components and the expected waiting time of failed components are derived. Finally, we present a special case of 6-out-of-10:G repairable system and study the influence of the vacation rate of repairman and the failure rate of repair facility on several performance characteristics. [ABSTRACT FROM AUTHOR]

In order to rationally perform the slope stability analysis, a fast procedure to determine the critical reliability slip surface (with the minimum reliability index) was proposed in this paper. The steps are as follows; a large number of potential slip surfaces are randomly generated and the correlation coefficients between the safety factors of potential slip surfaces and the deterministic critical slip surface are calculated. Based on the calculated coefficients, the slip surfaces whose correlation coefficients fall within a prescribed interval are categorized into one slip surface group. The 'pseudo' reliability indices of slip surfaces within one slip surface group are then calculated by fast Monte-Carlo method with only two samplings. The slip surface with the minimum 'pseudo' reliability index is regarded as the representative slip surface of the group. The critical reliability slip surface can be obtained by comparing those representative slip surfaces from all the slip surface groups. The case studies have shown that the fast Monte-Carlo method is applicable to soil slope reliability analysis. [ABSTRACT FROM AUTHOR]

In this paper, the rule that multiple synchronous vacations of c repairmen is firstly introduced into the k/n(G) repairable system. Suppose that the working lifetime of each component, the repair time of each failed component and the vacation time of each repairman, has an exponential distribution with the rate λ(> 0), μ(> 0) and θ(> 0), respectively. By using quasi birth-death process and matrix-geometric solution method, we discuss the steady probability that the system is in every state, and some performance characteristics, including some reliability indices queueing indices such as the steady availability, the steady failure frequency of the system and the waiting repair time of the failed component. Furthermore, the following four special cases: 1) c = 1, θ → +∞∞; 2) c = 1, k = 1, θ → +∞; 3) c = 1, k = n, θ → +∞∞; 4) c = 1, k = n - 1, θ → +∞∞, are discussed. Finally, we give the numerical example under the case c = 2, n = 6, k = 3, λ = 1/10, θ + 1/5, θ = 1/2. [ABSTRACT FROM AUTHOR]

Computation of the structural reliability index is one of the important factors in structural reliability theory. First-order second-moment algorithm often behaves discretely when the limit state surface is highly nonlinear. So rotation gradient algorithm is presented for computing the structural reliability. The method is based on Hasofer-Lind Rackwitz-Fiessler (HL-RF) algorithm, whose direction vector is determined by the linear combination of the negative gradient direction and former iteration direction vector. The numerical results show that the rotation gradient algorithm possesses the advantages of simplified iteration format and high convergence robust. The algorithm can ensure convergence and stability even the limit state surface is highly nonlinear. [ABSTRACT FROM AUTHOR]

Based on the clinical application data of medical X-ray computed tomography (CT) in the Shanghai Sixth People's Hospital, this study transformed it into the product reliability index requirements, and took the mechanical representative component-examination table (hereinafter referred to as "patient table") and the electronic representative component-DCB (data control board) as examples. Based on the relationship between failure characteristics and clinical application data, a complete set of closed-loop implementation methods from reliability index requirements to reliability design and verification are discussed.